The Dark Eco is a powerful substance in the Jak and Daxter series, and one of the two most powerful types of Eco. Dark Eco is often used by many villains in the Jak and Daxter universe.
Jak and Daxter: The Precursor Legacy
Dark Eco is Gol and Maia Acheron's primary source of power. The more intelligent Lurkers were also worshipers of Dark Eco and they used it as a weapon. Gol and Maia planned to transform the entire world by exposing all of it to Dark Eco. However, not only were their plans foiled by Jak and Daxter, but the pair of villains are presumably killed when falling into a Dark Eco silo outside their Citadel.
Jak 2: Renegade
In this game Jak is given the power to transform into a more monsterous form named Dark Jak due to being pumped full of Dark Eco. The primary villain Kor and his army of Metal Heads are also great manipulators of Dark Eco. A large quantity of Dark Eco was also a prize at the Haven City races.
Jak 3: Wastelander
The most powerful practitioners and controllers of Dark Eco emerged, they are named the Dark Makers who are corrupted Precursors and are controlled by some unseen overlord. In the game, Erol appears as their leader, having gained the ability to manipulate and control Dark Eco.